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EHV-1 Update: What You Need to Know
Amanda M. House, DVMDiplomate ACVIM (Large Animal)
Assistant Professor, UF CVM
Overview
● What is EHV?● How do horses get
EHV?● Signs of EHV infection
EHV O b k 2011● EHV Outbreak 2011 -Update
● Testing for EHV● Prevention of EHV
Equine Herpes Virus (EHV) EHV● EHV-1 : Abortion,
neonatal death, neurologic disease, respiratory disease
EHV 4 i● EHV-4 : respiratory disease, occasional neurologic disease
● Also known as “Rhinopneumonitis”
EHV
● Occurs throughout the world● Almost all horses > 2years old have been
exposedAft i iti l it h th bilit t● After initial exposure, it has the ability to become dormant and not produce clinical signs
● Horses that are latently infected probably act as source of infection for other horses
EHV Infections (Neurologic)
● Sporadic (usually <100/y)● Increasing prevalence● Highly contagiousg y g● Attack rate 33% (22-50%)● Mortality 40% (20-50%)● Difficult to control
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EHV
● ~80% horses probably infected
● Latent infections● Latent infections
● Lifelong infections
● Generally <7 d in environment
Clinical Signs of EHV-Respiratory/Non-neurologic
● Incubation period typically 2-10 days● Nasal discharge● Enlarged lymph nodes● Enlarged lymph nodes● Fever (can be up to 106 F!)● Limb edema (swollen legs), skin wheals
(25%)● Retinal hemorrhage
Clinical Signs of Neurologic EHV
● Limb weakness & ataxia• Symmetric• Worse in pelvic limbs
● Tail weakness● Perineal analgesia● Bladder distension or incontinence● Head tilt, facial paralysis (rare)● Seizures (rare)● Also called EHM- Equine Herpesvirus
Myeloencephalopathy
Ataxia (Uncoordinated Gait)
Equine Herpes Myeloencephalopathy Transmission of EHV
● Contagious! Spread by horse to horse contact via respiratory tract/nasal secretions
● Spreads indirectly through contaminated objectsobjects• Human hands or clothes• Contaminated equipment/tack/trailers/grooming
equipment• Contaminated feed and water buckets
● Can also be airborne
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EHV in the Environment
● Viable for about 7 days in normal conditions
● May survive up to 1 month
● Clean equipment before disinfecting
● EHV is sensitive to most disinfectants
● Hand washing/sanitizer
EHV-1 2011 Outbreak
● National Cutting Horse Association Western National Championship in Ogden, UT (April 29-May 8)
● Several horses develop EHV-1
● States that horses came from/went to were notified
EHV-1 2011
● Owners of horses known to have been exposed were contacted by state officials
● Suspect and confirmed cases are quarantinedT l f 84 CONFIRMED EHV● Total of 84 cases are CONFIRMED EHV or EHM in 10 states (AZ, CA, CO, ID, NM, NV, OK, OR, UT, WA)
● Of the 84, 58 were at the UT event● 12 horses have died or were euthanized
EHV- 1 2011
● 2,093 horses have been exposed from this outbreak (421 in UT at event, 1672 at secondary and tertiary premises)
● 78 additional suspect cases (not yet confirmed)● 78 additional suspect cases (not yet confirmed)● 240 exposed premises – 61 have suspect or
confirmed cases● USDA is updating all information:
http://www.aphis.usda.gov/vs/nahss/equine/ehv/
USDA Definitions
● Suspect EHV-1 case: A horse exposed to EHV-1 that develops a fever but no neurologic signs
● Confirmed EHV 1: Laboratory confirmation● Confirmed EHV-1: Laboratory confirmation of EHV-1 and no neurologic signs
● Suspect EHM: A horse exposed to EHV-1 that develops neurologic signs
● Confirmed EHM: Suspect case with laboratory confirmation
FLORIDA EHV-1● One farm in Alachua county
is under state quarantine● 2 horses euthanized due to
EHV-1 (one suspect case, one fi d )confirmed case)
● NO suspected exposure off affected premises
● NO link to UT event● http://www.freshfromflorida.
com/ai/index.shtml
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UF LAH Response Precautions● Admissions are asked
standard questions● Travel history?● Contact with horses from
W ?West?● Cutting horse, QH, Paint,
etc?● Presenting complaint?● History of fever or
neurologic signs?
Presumptive Diagnosis of Neurologic EHV
● Acute-onset hind limb ataxiaPLUS
● History of fever OR● Contact with a known or suspect case OR● Xanthochromic (yellow colored) spinal fluid
● THESE CASES MUST BE ISOLATED
Diagnosis of EHV
● Sample submission• Nasopharyngeal swab• Blood - Purple-top tube
● Viral isolation/identification• Virus isolation• PCR
● Serology• Acute (SN vs CF)• 4x increase in titer
Diagnostic Testing● Wear disposable gloves and change gloves between each horse ● Collect whole blood into EDTA and label sample (preferably have an
assistant label samples) ● If a twitch is used to restrain the horse it must be washed and
disinfected between horses ● Nasal swab collected using Dacron tipped swab with plastic shaft. Swab
h ld b i i h l f l l dshould be in contact with nasal mucosa for at least several seconds. ● Place swab in viral transport media or other transport solution
recommended by laboratory performing the test and label sample. Use a small volume of transport fluid (less than 2 mL) to avoid over-dilution of the sample.
● Perform hand hygiene between horses sampled and put on new pair of examination gloves
● Keep samples cool but not frozen and ship by overnight delivery ● Request real-time or nested PCR test and virus isolation● If sample reported as PCR positive, request typing of the virus
Treatment of EHV
● Supportive● Urinary catheter● Abdominal sling● Anti-inflammatories● Anti-inflammatories
• Flunixin• Corticosteroids?
● Anti-virals• Valacyclovir (Valtrex)• Ganciclovir
(experimental use)
Treatment of EHV● Valacyclovir
• In experimental study (OSU, Maxwell et al), Valtrex performed well when started within 2 days of infection
• Now available in US as a generic• Did not perform as well later in disease course
● Ganciclovir• In experimental study (OSU), did better at
halting progression of neurologic disease• EXPENSIVE
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Prevention of EHV● Vaccination
● Biosecurity
● Quarantine new arrivals• 21 days• Temperature BID
● Breeding farms• Disinfect between mares• Individual twitches?
Vaccination for EHV
● Vaccines are NOT effective (or labeled) for preventing neurologic disease
● Recommended for most horses that are● Recommended for most horses that are sport/performance/pleasure or exposed to other horses
● Recommended for ALL broodmares
Available Vaccines for EHV● Speak with your veterinarian about the best choice for
your horses
● Killed low antigen vaccines for EHV-1&4• Intervet, Pfizer, Boehringer
● Killed high antigen abortion vaccines• Pneumabort-K® (Pfizer) and Prodigy® (Intervet)• Superior performance with higher antibody responses and some
cellular response to vaccination
● MLV EHV-1 (Rhinomune®, BI)• Superior response (better clinical protection and reduced viral
shedding) when compared to low antigen vaccines (Goodman et al 2006), no results compared to high antigen vaccines
EHV Vaccination of Adults
● Recommended to prevent abortion in broodmares
• Give at 5, 7, 9 months gestation
● Reduce signs of respiratory disease in foals, weanlings, young performance horses
● 3 dose primary series
● Consider 6 month interval for young horses
EHV Vaccination of Foals
● Most foals will not mount a protective response to vaccination at 3-4 months of age if the mare has been vaccinated (Wilson et al)
● Foals of Vaccinated Mares• 3 dose series with inactivated or MLV at 5-6 months of age• 2nd dose 1 month later, 3rd dose 3-4 months later
● Foals of Unvaccinated Mares• 3 dose series with inactivated or MLV at 4-6 months
Biosecurity Practices
● Biosecurity means doing everything you can to reduce the risk of infectious disease being carried on your farm by people, animals, equipment, vehicles
● Management of exposed horses
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Management of Exposed Horses
● Take temperatures twice daily, isolate horses with fever ( T>101.5 F)
● Isolate horses returning from events if possible exposurepossible exposure
● Contact DVM if horse develops fever● Use separate equipment, hand sanitizers,
separate clothing, disinfectants
When Traveling with Your Horse
● Be sure vaccines are up to date● Bring your own buckets, equipment, leads● Strip old bedding if using stalls● Clean all organic material out of stall,
disinfect, add new bedding● Avoid communal feed and water sources● No nose to nose contact
Additional Resources
● http://www.abvma.ca/resources/documents/EquineBiosecurityPrinciplesandBestPracticesguide.pdf
● www aaep org● www.aaep.org● http://www.aphis.usda.gov/vs/nahss/equine/ehv/● http://www.freshfromflorida.com/ai/index.shtml● http://www.vetmed.ufl.edu/extension/equine/
Thank You!
● The Sanctuary
● Any Questions?